Metallic conduit



Aug. 16, 1932.

H. A. GARDNER 1,871,508

METALLIC CONDUIT Filed July 2, i930 Patented Aug. 16, 1932 HENRY A.GARDNER, OF WASHINGTON, DISTRICT OF COLUIIBIA mnmnmc connurr IApplication filed July 2, 1930. Serial H0. 465,441.

This invention relates to a method of and apparatus for protectingmetallic conduits. More particularly the invention relates to a methodof applying a protective coating of J corrosion inhibitive material tometallic conduits which are designed for use under ground and toapparatus for carrying out this method.

It is well known that a metallic conduit which is buried in the groundis subject to the destructive effects of many agencies, such as rustingdue to moisture in the ground, acid corrosion due to acid earthssurrounding the conduit, and electrolysis due to the presence ofelectric currents in the ground adjacent the conduit. The destruction ofan underground conduit such as is employed to conduct gas, or oil, or isemployed to protect electric wires or cables, entails not only aconsiderable expense for the materials and labor necessary to replacethe conduit, but endangers life and property where the conduit isemployed in conducting an inherently dangerous substance such as aninflammable or explosive fluid.

One of the objects of the invention is the provision of a method of andapparatus for protecting conduits from corrosion which is simple andinexpensive but at the same time efi'ective in all respects.

Another object of the invention is the provision of a method of andapparatus for protecting underground conduits from corrosion, and whichis particularly effective to prevent acid corrosion and electrolyticdisintegration.

tiv; casing comprising the present invention, an

Fig. 2 is a similar view of a modified form of the invention.

In practicing the invention, a seamless 5 tubular casing 1 of very thinsheet metal, such as twenty-two guage sheet steel, is disposed around aconduit 2 and is spaced uniormly therefrom by, a plurality of spacers 3,thereby providing an annular chamber 4 co surrounding the conduit. Aprotective material 5, which is preferabl in a fluent form (i. e.,liquid, semi-liqui granulated or powdered), whereby it can be poured, isintroduced into the chamber 4 through a filling as opening 6 in the topof the casing.

The casing is made in sections of suitable length which sections arejoined by telescoping adjoining ends. The ends may be joined in anyother suitable manner,so long as the joint is closed tightly enough toretain the protective material. The casing serves not only to retain theprotective material but protects the latter against puncture due tosharp rocks, and also prevents soil from sticking 7 to the protectivematerial, and prevents the protective material from being scraped oifthe conduit.

Where the conduit to be protected has already been installed and isbeing used, and so it is therefore undesirable to remove it, theprotective coating may be applied as shown in Fig. 2. The earth or othersubstance surrounding the conduit is removed from around the conduitthroughout a length greater than the length of the coating to beapplied. The conduit 2 is surrounded by a pair of cooperating U-shapedmembers'7, 8 of sheet metal, the adjacent edges 9, 10 of which arejoined by crimping whereby the members to form a substantiallycylindrical casing around the conduit 2'.

The space 4' between the casing 1' and conduit 2 is then filled with theprotective-material 5' which is introduced through the filling opening6'. Spacers 3' are provided as in the first form of the invention tospace the casing 1' from the conduit 2' and to prevent the lower side ofthe casing 1' from sagging.

This form of the invention may be emabsolutely necessary to provide afilling opening in this form of the invention as the excess material maybe forced out through the seam before the edges are completely crimpedtogether.

Preferably, the spacers take the form of nails made of zinc, oraluminum, or other metal which is electro-positive to iron, the nailsusually being provided as a part of the casing at the time ofproduction. In place of metallic nails, wooden pegs may be used,suitable openings being provided in the casing, if the casing walls aretoothick to permit the pegs to be driven therethrough.

Instead of nails or pegs, the spacers may be separate blocks joined toeither the casing or the conduit, or both, orthey may take the form offins integral with the casing, or with the conduit. If the spacers areformed as fins, it is necessary, of course, to provide openings in thespacers to permit the protective material to flow therethrough, wherebyall of the annular space between the conduit and casing will be filled.

Where the conduit is to be insulated electrically as well as protectedfrom corrosion, the casing and spacers are usually formed of insulatingmaterial such as phenolic condensate, or the wooden pegs mentioned abovemay be used. Instead of constructing the casing of insulating material,it may be constructed of metal and an insulating material employed asthe protective material. Where a very high degree of electricalinsulation is desired, both the casing and protective material may beinsulators. I

Where the protective material is plastic in form and/or it is desired toensure that it will fill all of the space between the conduit and thecasing, the protective material may be forced into the chamber underpressure. This may be accomplished by any well known pressure feedsystem, the delivery end of such system being attached to the fillingopening.

If desired, the conduit may be treated as described in my Patent No.1,230,475 before the protective coating is applied. Briefly stated, thistreatment consists in applying a film of tung oil paint to the surfaceof the conduit, partially drying the oil, and sanding the film before ithas hardened. This treatment provides an excellent binding surfaceforthe protective material and serves to increase the protective efi'ect ofthe same.

Parts A. Cementitious materials 1. Portland cement 1 Sand 2 Water"sufficient to make a thick slurry. 2. Lime hydrate 25 A Portland cementWater (or none) 3. Silicate of soda-40 Baum solution Solid pigments 30Sand (or none) I 4. Litharge Glycerine 20 B. Thermo-plastic materials 1.Rosin (or other resin) 2. Asphalt (or bitumen) 3. Bichromate of soda (orpotash) Water Gelatin (or glue) suflicient to make a stiff jell whencool. C. Cellulosic materials 1. Viscose solution (cellulose xanthate)2. Alkali cellulose dispersed in water. 1). Rubber materials 1.Rubber-toluol solution stiffened with zinc pigment 2. Rubber latexsolution E. Alkali-forming materials 1. Caustic soda (or potash) meltedFiller (or none) 2. Cyanamid (or carbide)-dry or as a slush formed bymixing with organic liquids. F. Pigment and vehicle 1. Chromate of zinc(or other rust inhibitive pigment) Oil (or water) sufiicient to form apaste.

It should be obvious that the invention provides a-method of andapparatus for satisfactorily protecting metallic conduits from corrosionwhich is simple and inexpensive and which may be adapted to a largenumber of applications.

Although I have described the invention with reference to particularillustrative embodiments, yet I do not wish to limit the invention tosuch embodiments and I desire that the appended claim be accorded thebroadest interpretation consistent with its wording and the prior art.

mamas I claim:

The combination with a ferrous member, of a coating of corrosioninhibitive material disposed on the surface of said member, a

metallic jacket disposed over said coating for retaining the same onsaid ferrous member, and means comprising a plurality of nails formed ofa metal which is electropositive to iron extending through said jacketinto contact with said ferrous member for spacing said jacket from saidferrous member.

In testimony whereof, I afiix my signature.

HENRY A. GARDNER.

